Bug 1289075

Description of problem:
Include the reason/s for failing to apply changes for 'network' on 'host' in the event log in UI.

Today, the reason appears only in the engine.log. But in the event log UI, we just see:
'(1/1): Failed to apply changes for network(s) lb2 on host silver-vdsb.qa.lab.tlv.redhat.com. (User: admin@internal)'

without any reason. And user need to try and understand what is the reason and why the change is failed. 
This can happen for a multiple reasons such:

1) 2 Networks attached to 1 NIC. one is non-vlan VM network and one is vlan network. Changing the vlan network to be non-vlan will fail to apply changes for this network on the host(2 VM networks can't live together on 1 NIC) and the network will considered as unsynced. 
2) 2 networks attached to 1 NIC. change one of the networks to a custom MTU(9000 for example). This will fail to apply changes as well. 
3) 2 networks attached to 1 NIC. Configure 1 network with a Host QoS entity. This will fail to apply changes as well.

In all of the above scenarios, the reason is not mentioned in the UI event log, only in the engine.log and user have no idea why the changes didn't took place.

Version-Release number of selected component (if applicable):
3.6.1.1-0.1.el6

How reproducible:
100

Steps to Reproduce:
1. Look at description above ^^ 
2. ''
3. ''

Actual results:
Reason for the failing is not included in the event log UI. 

Expected results:
Include the reason/s for failing to apply changes for 'network' on 'host' in the event log in UI 

- As agreed with QA and DEV, such operation/scenarios , like described above won't be blocked by engine. So the reason for failing in the event log UI is very important for the admin/user to understand why/what/which(network,host).